Review Reports - Substitution of Inorganic Fertilizer with Organic Fertilizer Influences Soil Carbon and Nitrogen Content and Enzyme Activity under Rubber Plantation

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Title: Substitution of inorganic fertilizers with organic fertilizers
influences soil carbon and nitrogen content and enzyme activity under rubber
plantation

Dear Authors

The subject is very interesting and corresponding to the Forests journal’s profile. The manuscript presents the possibilities of using organic fertilizers on rubber plantations. The aim of conducted study was elucidate the influence of partial substitution of inorganic fertilizer with organic fertilizers on soil organic carbon and nitrogen properties and SOC and N converting enzyme activity. General value of the MS is good.

General remarks

In order to increase the usefulness of the article, Authors must refer to the following points. Additions should be made to increase the scientific value of the manuscript.

1. Abstract: When using abbreviations in a manuscript for the first time, an explanation should also be provided.

2. Materials and methods: Line 89 - Soil type should be provided according World Reference Base for Soil Resources 4^th edition, 2022. What superphosphate was used? In the case of mineral fertilizers, chemical formulas, names and % content of the ingredient should be provided. Line 116 - Are you sure the soil was sifted through a sieve with a mesh diameter of 0.149 mm?

3. The Results and Discussion sections are well presented.

4. Conclusions: I suggest adding a few details in the conclusions. For example: % increase in the analyzed parameters due to the use of organic fertilizers. Do the authors see the need for further research? If so, in what direction?

Specific comments

Line 45 – it should be: According to Salehi et al. [8],……

Line 127 – it should be: Using the DeForest [17]……

Line 144 – it should be: (Figure 1A)

Line 149 – it should be: Figure 1B.

Line 157 – it should be: (Figure 1 CD).

Lines 238 and 282 – it should be: Figure 4

Best regards

Author Response

Response to Reviewer comments (Manuscript No. forests-2964493)

This is a revised manuscript of forests-2964493. The manuscript has been revised, and the responses to the comments have been addressed as below.

Dear Editor and Reviewers,

We are very grateful to the Editor and reviewers for taking the time to review our manuscript. We deeply appreciate the reviewer's valuable comments, suggestions, and questions about improving our manuscript. Please find below our itemized responses to these suggestive questions. We have revised our manuscript according to the Editor and reviewer suggestions and hope our responses will be satisfactory and that the manuscript has been improved significantly. We hope that the revised manuscript will fully meet the standards of publication in your journal after this minor revision. Your suggestions, corrections and comments were highlighted in blue color in the revised manuscript.

Comments from the Editor and Reviewers:

The subject is very interesting and corresponding to the Forests journal’s profile. The manuscript presents the possibilities of using organic fertilizers on rubber plantations. The aim of conducted study was elucidate the influence of partial substitution of inorganic fertilizer with organic fertilizers on soil organic carbon and nitrogen properties and SOC and N converting enzyme activity. General value of the MS is good.

General remarks

In order to increase the usefulness of the article, Authors must refer to the following points. Additions should be made to increase the scientific value of the manuscript.

Response: We are thankful to Editor and reviewers for taking the time to review our manuscript. Below are the point-to-point responses to reviewers' comments, suggestions, and questions.

Abstract: When using abbreviations in a manuscript for the first time, an explanation should also be provided.

Response: We are thankful to the reviewer for this valuable suggestion. As the reviewer suggested, we explained all abbreviations that are used for the first in the manuscript. Please have a look at the details in the revised version of the manuscript.

Materials and methods: Line 89 - Soil type should be provided according World Reference Base for Soil Resources 4th edition, 2022. What superphosphate was used? In the case of mineral fertilizers, chemical formulas, names and % content of the ingredient should be provided. Line 116 - Are you sure the soil was sifted through a sieve with a mesh diameter of 0.149 mm?

Response: Thank you very much for the suggestions, corrections, and questions. I added the relevant reference to the mentioned sentence of soil type. Please see the revised manuscript.

Schad, P. World Reference Base for Soil Resources—Its Fourth Edition and Its History. Journal of Plant Nutrition and Soil Science 2023, 186, 151–163, doi:10.1002/jpln.202200417.

What superphosphate was used? In the case of mineral fertilizers, chemical formulas, names and % content of the ingredient should be provided

Response: We apologize for not mentioning the complete information on inorganic fertilizers. We used “ super phosphate for phosphorus, Urea for nitrogen, and potassium chloride for potassium. The chemical formula and name information are also provided in the given section. Please see line 106 -109 in the revised manuscript.

“Using the local conventional farming practices, we applied 1.0 kg of chemical fertilizer containing 15 % N as urea (46 % N), 9 % P as single superphosphate (12 % P₂O₅), and 6 % K as potassium chloride (60 % K₂O)”

Line 116 - Are you sure the soil was sifted through a sieve with a mesh diameter of 0.149 mm?

Response: Yes, we used a 0.148 mm mesh diameter sieve the soil for Soil organic carbon determination according to the method of Xu et al. (2023). For more details, please see the below article.

Xu, W.; Liu, W.; Tang, S.; Yang, Q.; Meng, L.; Wu, Y.; Wang, J.; Wu, L.; Wu, M.; Xue, X.; et al. Long-Term Partial Substitution of Chemical Nitrogen Fertilizer with Organic Fertilizers Increased SOC Stability by Mediating Soil C Mineralization and Enzyme Activities in a Rubber Plantation of Hainan Island, China. Applied Soil Ecology 2023, 182, 104691, doi:10.1016/j.apsoil.2022.104691.

The Results and Discussion sections are well presented.

Response: We are thankful to the Editor and reviewers for taking the time to review our manuscript.

Conclusions: I suggest adding a few details in the conclusions. For example: % increase in the analyzed parameters due to the use of organic fertilizers. Do the authors see the need for further research? If so, in what direction?

Specific comments

Response: Thank you very much for your suggestion. we have revised the conclusion, added the % increase of the analyzed parameter, and added future research direction. Please see the revised manuscript for more details.

“Our study explored the influence of partial substitution of inorganic fertilizers with organic fertilizers on soil physicochemical characteristics, SOC and nitrogen concentrations, and soil enzyme activity under natural rubber plantations. The results clearly indicate that utilizing organic fertilizers to partially replace chemical fertilizers has a significant impact on the nutrient content. The influence is primarily achieved through alteration in SOC and nitrogen concentrations, nitrogen mineralization, and soil enzyme activity. Notably, at 0-10 depth, the 50% manure and 75% manure treatments significantly increased the SOC (7.15 % and 3.46%) total nitrogen (3.92% and 0.98 %) and mineral nitrogen (6.46%, 11.49%), as well as soil enzyme activity (BG 18.55% and 27.33%), (NAG 11.16 % and 26.54%) and (LAP 17.83 % and 18.82%), compared to CK. The results showed that in a rubber plantation on Hainan Island, replacing inorganic fertilizers with organic fertilizers could help preserve soil organic carbon stability, nitrogen concentration, and enzyme activity. We recommended considering that 50 % or 75 % organic fertilizers with inorganic fertilizers could be an optimal strategy to enhance nutrient availability for sustainable agricultural production in Hainan Island. Therefore, more attention should be paid to the dynamics of soil nutrient and enzyme activities in rubber plantation soil profiles under different climatic conditions after the co-applications of inorganic fertilizer and manure.”

Line 45 – it should be: According to Salehi et al. [8],……

Line 127 – it should be: Using the DeForest [17]……

Line 144 – it should be: (Figure 1A)

Line 149 – it should be: Figure 1B.

Line 157 – it should be: (Figure 1 CD).

Lines 238 and 282 – it should be: Figure 4

Response: Thanks, revised as suggested. Please see the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

Your manuscript seems interesting because it show effect of substitution of inorganic fertilizers with organic fertilizers on carbon and nitrogen content in soil and enzyme activity in rubber plantation. The layout of the articles became standard for research papers.

However, I have a few comments, doubts and observations:

General comments:

Are the treatments (50% and 75% M) practical and economic? Is there sufficient cow manure production on Hainan Island? Do the authors plan to test other organic fertilizers, pig manure or compost?

Detailed comments

1. Abstract. It is good practice to explain abbreviations that appear for the first time in the manuscript. Dots cannot be used in units, e.g. mg.kg à mgkg. This note applies to the entire manuscript.

2. Keywords: Specify what "nitrogen". Organic? Total? Assimilable? Mineral?

3. L. 89: There is no citation for the USA Soil Classification

Good luck!

Sincerely yours

Reviewer

Author Response

Response to Reviewer comments (Manuscript No. forests-2964493)

This is a revised manuscript of forests-2964493. The manuscript has been revised, and the responses to the comments have been addressed as below.

Dear Editor and Reviewers,

We are very grateful to the Editor and reviewers for taking the time to review our manuscript. We deeply appreciate the reviewer's valuable comments, suggestions, and questions about improving our manuscript. Please find below our itemized responses to these suggestive questions. We have revised our manuscript according to the Editor and reviewer suggestions and hope our responses will be satisfactory and that the manuscript has been improved significantly. We have revised our manuscript by an English native speaker who critically corrected the text for English writing and updated it with better grammar and spelling. We hope that the revised manuscript will fully meet the standards of publication in your journal after this minor revision. Your suggestions, corrections and comments were highlighted in red color in the revised manuscript.

Comments from the Editor and Reviewers:

However, I have a few comments, doubts and observations:

General comments:

Are the treatments (50% and 75% M) practical and economic? Is there sufficient cow manure production on Hainan Island? Do the authors plan to test other organic fertilizers, pig manure or compost?

Response: Thank you very much. It is a very good question. Yes, the treatment of 50% and 75% organic fertilizers is economical, cheap, and easily available. Using only chemical fertilizers is expensive, so combining half (50%) or one-third (75%) of organic fertilizers with chemical fertilizers is the best practical approach. Besides, organic fertilizers are environment-friendly and have no ecological consequences like nutrient imbalance, soil acidification, and low soil fertility. Yes, there is sufficient cow manure production on Hainan Island. Because our research site is located in Zhubi farmland, Baisha County, Hainan Island, and Zhubi County, where most farmers are living, animal manure is easily and in sufficient amounts available. In the current research, we used cow manure as an organic fertilizer. In the future, we will also prefer to use other manure compost, such as pig manure, chicken manure, etc.

Detailed comments

Abstract. It is good practice to explain abbreviations that appear for the first time in the manuscript. Dots cannot be used in units, e.g. mg.kg à mgkg. This note applies to the entire manuscript.

Response: We are thankful to the reviewer for this valuable suggestion. As the reviewer suggested, we explained all abbreviations used for the first in the manuscript and revised the units. Please look at the details in the revised version of the manuscript.

Keywords: Specify what "nitrogen". Organic? Total? Assimilable? Mineral?

Response: Thank you very much for your suggestion revised as suggested, I used mineral nitrogen

89: There is no citation for the USA Soil Classification

Response: Thank you very much for the correction. I have added the relevant reference to the mentioned sentence of soil type. Please see the revised manuscript.

Schad, P. World Reference Base for Soil Resources—Its Fourth Edition and Its History. Journal of Plant Nutrition and Soil Science 2023, 186, 151–163, doi:10.1002/jpln.202200417.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

General Comments

Problem with the units:

„%M” unit is confusing . I recommend to use % manure

line 104 5.76 “g.kg^-1” , „nmol.g^-1.h^-1” use the dots in the middle

Incorrect chemical formulas:

line 94, table 1 “NH⁺₄-N” change to NH₄⁺-N

line 111 table Ca(H₂PO₄)2.H₂O The dot must be in the middle before the crystalline water

line 118 - line 210 The ion charges in the middle, are not in superscript.

Other comments:

Figure 4. Which treatment was used control or NPK?

semi-micro-Kelvin method the reference is missing.

The total nitrogen exactly how was determined?

The available nitrogen is missing. Why not determined?

Line 119 acetylglucosaminidase (NAG) change to N-Acetyl-glucosaminidase (NAG)

Material and methods

The reference for the L-leucine aminopeptidase (LAP) determination is missing. The DeForest (2009) reference does not contain it. The citation number is missing.

I recommend carefully checking the manuscript again.

Author Response

Response to Reviewer comments (Manuscript No. forests-2964493)

This is a revised manuscript of forests-2964493. The manuscript has been revised, and the responses to the comments have been addressed as below.

Dear Editor and Reviewers,

General Comments

Problem with the units:

„% M” unit is confusing . I recommend to use % manure

line 104 5.76 “g.kg-1” , „nmol.g-1.h-1” use the dots in the middle

Response: Thank you very much for the suggestions. I corrected the units in the entire manuscript as suggested.

Incorrect chemical formulas:

line 94, table 1 “NH+4-N” change to NH4+-N

Response: Thank you very much for the suggestions. I corrected the incorrect formula in Table No. 1, as suggested.

line 111 table Ca(H2PO4)2.H2O The dot must be in the middle before the crystalline water

line 118 - line 210 The ion charges in the middle, are not in superscript.

Response: Thank you for your correction. The phosphate fertilizer's chemical formula was corrected; please see the revised manuscript.

Other comments:

Figure 4. Which treatment was used, control or NPK?

Response: Thank you very much for your question. we consider control treatment for Figure 4

semi-micro-Kelvin method the reference is missing.

The total nitrogen exactly how was determined?

Response: Thank you very much for your correction. We have added the semi-micro Kelvin method to the revised manuscript. For more details please a look the below article

The total nitrogen content of the soil was extracted by the semi-micro-Kelvin method and determined by a fully automated flow analyzer, and the content of ammonium nitrogen and nitrate nitrogen in the soil was extracted by KCl and determined by automatic flow analyzer (Proxima1022/1/1, Alians Scientific Instruments, France

Olsen, S.R., Sommers, L.E. Methods of Soil Analysis, Part 2, Chemical and Microbial Properties Agronomy Society of America, Agronomy Monograph 9, Madison, Wisconsin; 1982;

The available nitrogen is missing. Why not determined?

Response: Thank you very much for pointing out that we had not included available nitrogen in this manuscript because of the available nitrogen data we had already published from the same research site.

Line 119 acetylglucosaminidase (NAG) change to N-Acetyl-glucosaminidase (NAG)

Response: Thank you so much for the correction. We have changed the acetylglucosaminidase (NAG) to N-acetyl-glucosaminidase (NAG) in the revised manuscript.

Material and methods

The reference for the L-leucine aminopeptidase (LAP) determination is missing. The DeForest (2009) reference does not contain it. The citation number is missing.

Response: Thank you very much for the correction. We have added the reference for L-leucine aminopeptidase (LAP) in the revised manuscript.

Saiya-Cork, K..; Sinsabaugh, R..; Zak, D.. The Effects of Long Term Nitrogen Deposition on Extracellular Enzyme Activity in an Acer Saccharum Forest Soil. Soil Biology and Biochemistry 2002, 34, 1309–1315, doi:10.1016/S0038-0717(02)00074-3.

I recommend carefully checking the manuscript again.

Response: Thank you very much. We have revised our manuscript by an English native speaker who critically corrected the text for English writing and updated it with better grammar and spelling.

Author Response File: Author Response.pdf